Encapsulating a crawl space is a common way to deal with moisture or flooding. It is also an easy way to quickly get control of the air quality in the home and lockout rodents and insects. When you’re thinking about “green-ovating” your home, or simply getting control of the moisture or humidity, when you have a crawl space, you must encapsulate.
Encapsulation does a great deal for the crawlspace and for the home above.
What the process is and what it does
The practice of encapsulating or “sealing off” a crawlspace is done to lock out moisture and cut off the connection between moisture, water and the joists of a home. By running a vapor barrier down the walls of a crawl space to completely cover the floor, you essential separate the outside from the inside of the home.
This vapor barrier will be the flexible membrane between the walls and floor and the rest of the home. A properly designed vapor barrier will limit the transfer of moisture through it while regulating the speed at which air will naturally pass through. This helps to limit and control the amount of moisture that will find its way into the air space and completely segregate liquid water and direct it to a sump location.
5 helpful tips when having a Vapor Barrier installed in your crawlspace:
1.) Not all vapor barriers are made for this task – careful. There are many products out in the world that claim to be able to fully encapsulate a crawl space. Make sure that your vapor barrier has a low “perm” rate and that it is at least 14mil thick. If you’re planning to use the space for storage make sure that a flexible sub-flooring product is also placed on top of the vapor barrier to protect it.
2.) Cover the walls too – all too often contractors forget to also encapsulate the walls of the crawl space when installing a vapor barrier. This can still allow water and moisture into the basement and therefore render the whole project useless. Take care to make sure it’s installed properly.
3.) Don’t use sprays. – Sealants and sprays aren’t designed to be applied on the interior of the basement. They are good in many circumstances as the “first line of defense” but as the last, they can’t hold the pressure and moisture trapped in a wall.
4.) Install a sump and a dehumidifier – to totally control the moisture level in the crawl space it’s imperative that you have a sump pump and a dehumidifier installed. Moisture will still exist, although not to dangerous levels, but a sump will remove any liquid water your encapsulation traps, and the dehumidifier will deal with any residual moisture that naturally collects in the space.
Crawlspace Moisture Control - The Case for Encapsulation
Owning a home with a basement can give us additional living space that is not typically available in a home with a crawl space. Many people put recreational rooms in the basement as well as using them for storage and often as a personal workshop. It may be difficult, however, whenever water in the basement becomes a problem. There are really two different ways in which water can invade this area of our home, both of which will take some form of waterproofing to correct. They can either come in slowly, almost undetected by us or it can quickly invade our basement and cause it to be flooded.
Since the basement is below ground level, moisture is often a problem, even if it is not visible. It may show up as mold or mildew that begins to appear on the walls and although you cannot actually see the moisture that is present, there are plenty of telltale signs that will help to identify the fact that you have a problem.
Doing a little bit of basement waterproofing for this usually means putting a specific type of paint on the walls or perhaps even spraying them down with chemicals so that they are impervious to mold growth. It may also help if you run a basement dehumidifier on a regular basis, even after you have completed the basement waterproofing project.
The other way that water can invade our basement is all at one time which can cause it to be flooded. I have personally had a difficulty with this for many years and it can be destructive, especially if you use the basement for living space or storage. If the water is coming in at one specific location, sealing that location in some way or another may help to cure the problem a little bit.
There may be times, however, whenever more drastic measures need to be taken. If you're basement floods on a regular basis, you may need to dig down to the bottom of your foundation on the outside of the walls and install a French drain. This will divert any water away from the house so that it does not end up in your basement.
Having a problem with water in your basement is simply keeping you from enjoying part of your house. Although waterproofing your basement is going to take a little bit of work, it will all be well worth the effort whenever you can take this part of your home back again.
A Closed, Sealed Crawlspace - What a Really Bad Idea
There are advantages and disadvantages in having a crawl space under your home. Advantages, perhaps, a slightly elevated home may be more attractive than a home on a slab. Plus, you can make repairs and modifications to plumbing, heating, and electrical services.
Disadvantages, a crawl space is an area that is never cleaned. Under the vapor barrier the humidity is always 100% so mold and bacteria are always present. Termiticides, other chemicals, even rodent droppings may be present, and odors and gases that emanate will migrate into the home's living space unless proper ventilation is installed. Whether on a slab or elevated, if radon is present, good ventilation is required.
There are several technologies on the market in regard to moisture control. One is encapsulation, sealing the crawlspace. Though this might lower humidity, it's costly and there is no dilution or replacement of stagnant, poor quality air. Again, if radon is present, ventilation is required.
Another technology is to install a dehumidifier in the crawl space. This can lower humidity, but again will not dilute or replace the stagnant air. Another point to think about is that the dehumidifier will be costly to operate. More importantly, using a dehumidifier requires you to close tightly the crawl space. Thus, the home's living space air quality is going to be lowered because the crawl space air is not diluted and replaced with fresh outdoor air.
Some systems use a dehumidifier control (dehumidistat) to operate a crawl space vent fan. This sounds like it's going in the right direction. However, the technology isn't quite right. Here's why. Suppose the outdoor air is getting worse (wetter). Though the dehumidistat control is in the crawl space, it will quickly recognize this wetter air condition and begin ventilation, even though ventilating is going to make crawl space wetter. Another problem with a dehumidistat control is that most of them are not made for the difficult environment of a crawl space, so their warranties are short, 30 days to 1 year maximum for the dehumidistat.
There is another system that uses special technology different from all the others mentioned above. This special technology makes a comparison of the actual moisture content of both the air inside the crawlspace and the outdoor air. The result is that it pauses and does not ventilate when bringing in outdoor air is going to make the space wetter. Then, as the outdoor air is getting drier and is able to improve the moisture and air quality in the crawlspace, then this ventilator moves a lot of air which dilutes and replaces stagnant air, ultimately improving your home's living space air quality.
This system, called the Smartvent, is made in the USA, is used from Florida to Alaska... San Diego to Nova Scotia.
This system is a proven system, and it is the only system to have undergone a year long test where crawl space humidity averaged 46%. Besides the unique technology this system employs, it also has the longest warranty of all ventilators, five years.